And that's all there is too it? Excellent, thanks again.
I was remembering when a colleague had his battery powered laptop connected to some industrial cabinet by a rs232 cable, battery was running low, he connected the power brick and things went pop. Didn't want to risk popping people.
It's possible the RS232 output isn't isolated and connecting it to the earthed industrial equipment caused a short circuit.
You have to be a bit careful, on some power supplies you can measure ~150V between output and mains earth with a good digital multimeter, assuming the power supply is a class II type (not earthed - double insulated). The current is very low, but might be felt by some. The standards bodies set limits on 'Touch current'; BSEN 60990 shows some ways to measure it.
Yes, under certain conditions, it's possible to feel a tingle, especially if the current passes through a small area of the body with a high density of nerve endings, such as the fingers. This is only a problem if the appliance is used in a hospital, where there's a risk the current could pass straight through the heart, in which case this is easily remedied by connecting it to an isolation transformer.
The main hazard to electrical equipment is ESD, that 150V is enough to destroy the gate of a MOSFET, although proper design can protect against this.